1. Field of the Invention
The present invention relates, generally, to an injection molding machine, and more particularly, but not exclusively, the invention relates to three level stack mold injection molding machine.
2. Background Information
The state of the art includes U.S. Pat. No. 5,707,666 that provides a four level mold having linkage for moving the molds that is capable of moving the molds simultaneously and in unison so that the molds open and close together. The linkage would not permit the use of a side entry robot nor does it show open and easy access through the top of the machine.
U.S. Pat. No. 5,518,387 describes a swing arm device for removing parts from a mold. The motion of the swing arm device is synchronized with the opening and closing of the mold to speed up part retrieval.
U.S. Pat. No. 5,185,119 shows a stack mold in Tandem configuration with cores aligned the same way. In this machine the mold is operated on alternate cycles so each side opens sequentially rather than simultaneously.
U.S. Pat. Nos. 6,027,681 and 6,099,784 describe a stack mold that has unequal strokes so that different parts can be molded in the adjacent molds.
U.S. Pat. No. 6,155,811 describes a two level mold that is mounted on linear bearings. This is the type of machine that has been modified by the present invention to provide a three level stack mold in the space occupied by the two level stack mold described in this patent.
U.S. Pat. Nos. 5,908,597 and 6,036,472 describe multiple stack mold machines that use rack and pinion devices to open and close the mold and includes part ejection means that is operated independently of the rack and pinion devices.
An article on page 14 of the September, 1991 issue of Plastics World describes a mold change system that includes self-locating/leveling mold guide slots.
An article by P. Glorio of Incoe Corp. published in ANTEC '88, pages 255 to 258 describes the development of quick mold change systems including systems that use hydraulically actuated wedge-lock clamps.
U.S. Pat. No. 4,473,346 describes a single level molding system where the molding dies are insertable and removable in either the horizontal or vertical direction.
U.S. Pat. No. 4,500,274 describes a quick-change mold system that includes adapter plates provided with service fittings that interconnect and disconnect upon insertion and removal of the molds together with the adapter plates.
U.S. Pat. No. 4,500,275 describes a quick-change mold system that includes a locator clamp for facilitating the insertion and removal of a mold from a molding machine
U.S. Pat. No. 4,568,263 describes the use of locator wedge clamp assemblies mounted on and extending from the platens
U.S. Pat. No. 5,096,404 describes the use of rollers and guide rails for aligning a mold press in a vertical plane above the injection molding machine.
U.S. Pat. No. 5,096,405 describes a mounting plate attachable to a molding machine platen. The mounting plate has a plurality of retention slots with hydraulically actuated clamps in the slots. Actuation of the clamps presses a mold part toward the platen in an adjusted position.
With the cost of injection molding machines and the competitive pricing of products made thereon, it is essential that the machine be as productive as possible. In the case where the machine must be capable of making a number of different parts, this requires that mold changes be quick and inexpensive. It is also cost effective to minimize the space requirements of the machine. In addition, it is essential that parts be removed from the molds as quickly as possible so the cycle time of the machine can be as short as possible. It is also advantageous to provide a machine that requires only a single set of hot runner plates for all moldsets usable on the machine.
The present invention provides an injection molding machine that enables mold changes to be made quickly and easily, provides robot accessibility to the parts that may be of a variety of heights without modifying the space requirements of the mold and allows a three level stack mold for high profile parts to be placed in space that was previously fully occupied by a two level stack mold.
The invention is achieved by creating a three level stack mold that provides open access to the molds from all sides when the molds are open. Side access is provided by designing a linkage for the stack mold that surrounds the mold opening but does not cross it when the molds are open. Moving all physical connections such as water and electrical lines to the side edges of the mold provides access through the top and bottom. To avoid any electrical faults caused by water leaks from occurring, the electrical connections are made at the top of the mold and the water connections at the lower point of the mold. Air connections are also provided at the top of the machine to avoid or minimize contamination of the air lines by a failure in the water supply system.
When the molds need to be changed, the mold is closed and each cavity plate is latched to its respective core plate. The mold is then opened and each moldset of a cavity plate and a core plate is removed from the machine as a single unit along guides. When the cavity and core plate moldset is fully removed, a new moldset of a cavity plate and a core plate is inserted into the mold and guided by the same grooves. The grooves guide the core plate so that it is slightly separated from the platen until it is very near its home position. When it reaches this position a wedge surface forces the core plate against the platen and automatically locks it into position on the platen. At the same time the air and water connections automatically connect to the core plate by automatic docking mechanisms. When the core plate is in position, the mold is closed and the cavity plate is disconnected from the core plate and firmly attached to the hot runner plate.
The invention also provides a machine in which all three moldsets in the three level stack mold are oriented in the same direction. This enables uniform robot actuation for all three moldsets without the need to reorientate molded parts. This further simplifies the retrieval of molded parts.
With this configuration, the robot can be located in the same position for all parts and enter between the cavity and core faces without interference with either face. The linkage assembly surrounds the mold opening when the mold is open and eliminates the need for robot adjustment when the molds are changed. This also provides weight distribution and manufacturing benefits.